Cable preparation tool

ABSTRACT

The present invention is a cable preparation tool which allows the preparation of a coaxial cable having a corrugated outer conductor to receive a connector in one step. The tool allows for the control of trim dimensions for each component of the cable without measuring. No matter whether the end of the cable before preparation is at the crest or valley of the outer conductor, the tool provides the correct trim dimensions for each component and stops cutting when these dimensions are reached. The cable preparation tool includes a main body having a cable receiving end, cable receiving area for stripping of the cable such that the crests and valleys are exposed, and a crest and valley locating system as part of the main body for locating the exposed crests and valleys of the corrugated conductor. The crest and valley locating system includes at least one valley locator unit extending into the cable receiving area and a spring that biases the valley locator unit into the cable receiving area. The valley locator unit moves away from a crest of the cable as the crest contacts the valley locator unit and rebounds into the next valley due to the biasing of the spring during insertion of the cable.

This application is a divisional application from U.S. patentapplication Ser. No. 09/370,627 filed on Aug. 6, 1999, now U.S. Pat. No.6,397,474.

BACKGROUND

The present invention relates to the preparation of a coaxial cable forthe fitting of a connector, especially coaxial cable having a corrugatedouter conductor. Examples of coaxial cables using a corrugated outerconductor are shown in FIGS. 1-3. The components of the corrugated outerconductor coaxial cable are a center conductor 10, dielectric 12, outerconductor 14 and an outer jacket 16. FIGS. 1 and 2 shows the centerconductor 10 as a solid conductor for cable 1 and as a hollow conductorfor cables 2, 3. The outer conductor 14 is of a corrugated material.When a cable having a corrugated outer conductor is prepared to receivea connector, a hack saw is usually used to cut the cable to theapproximate termination length. More precise preparation of the variouscable components is then performed per the connector manufacturer'sspecifications. Manufacturer's specifications usually call for uniquetrim dimensions of the outer jacket, outer conductor, dielectric andcenter conductor. The trim dimension of each cable component depend onthe connector to be used. The trim dimension of any given cablecomponent is often given in reference to another cable component. Morespecifically, for example, the trim dimension of the outer jacket mayrefer not only to a specific number (x) of bare corrugations of theouter conductor 14 required, but whether the reference point is at thecrest 18 or valley 20 of a specific corrugation. Generally, for mostconnectors, the trimming of the outer conductor is required at a crestof the corrugated material. Providing the proper trim dimension for eachcable component requires the use of off-the-shelf hand tools (includingbut not limited to a tape measure, scribe, knives, diagonal cutters,pliers, hack saw, wire or nylon brush) used individually to separatelyprepare the different cable components. It is desired by a technician tohave one tool to perform the trimming of all the cable components in onestep when preparing a cable end for a connector.

It is an object of the present invention to provide a cable preparationtool which removes the proper amount of all the components of a coaxialcable to receive a cable connector in one step without the use of othertools.

SUMMARY OF THE INVENTION

The present invention is a cable preparation tool for stripping acoaxial cable having a corrugated conductor that includes crests andvalleys. The cable preparation tool includes a main body having a cablereceiving end, cable receiving area for stripping of the cable such thatthe crests and valleys are exposed, and a crest and valley locatingsystem as part of the main body for locating the exposed crests andvalleys of the corrugated conductor. The crest and valley locatingsystem includes at least one valley locator unit extending into thecable receiving area and a spring that biases the valley locator unitinto the cable receiving area. The valley locator unit moves away from acrest of the cable as the crest contacts the valley locator unit andrebounds into the next valley due to the biasing of the spring duringinsertion of the cable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of three cables having a corrugatedconductor according to the present invention;

FIG. 2 is another perspective view of three cables having a corrugatedconductor according to the present invention;

FIG. 3 is a side view of three cables having a corrugated conductoraccording to the present invention;

FIG. 4 is a side view of a first embodiment of a cable preparation toolaccording to the present invention;

FIG. 5 is an attachment end view of the cable preparation tool of FIG. 4according to the present invention;

FIG. 6 is an exploded side view of the cable preparation tool of FIG. 4according to the present invention;

FIG. 7 is an cable receiving end view of the cable preparation tool ofFIG. 6 according to the present invention;

FIG. 8 is an exploded side view of the cable preparation tool of FIG. 4according to the present invention with an additional blade in the side;

FIG. 9 is an attachment end view of the cable preparation tool of FIG. 8according to the present invention;

FIG. 10 is a cut through view of the cable preparation tool of FIG. 8according to the present invention;

FIG. 11 is a side view of a first embodiment of a cable preparation toolaccording to the present invention;

FIG. 12 is an attachment end view of the cable preparation tool of FIG.11 according to the present invention;

FIG. 13 is a side view of a second embodiment of a cable preparationtool according to the present invention;

FIG. 14 is a cut through view of the cable preparation tool of FIG. 13according to the present invention;

FIG. 15 is an exploded side view of the cable preparation tool of FIG.13 according to the present invention;

FIG. 16 is an exploded and cut through attachment end view of the cablepreparation tool of FIG. 15 according to the present invention;

FIG. 17 is a cut through attachment end view of the cable preparationtool of FIG. 15 according to the present invention;

FIG. 18a is an attachment end view of a third embodiment of the cablepreparation tool according to the present invention;

FIG. 18b is an attachment end view of the main body of a fourthembodiment of the cable preparation tool according to the presentinvention;

FIG. 18c is a side view of the cable preparation tool of FIG. 18baccording to the present invention;

FIG. 18d is an attachment end view of the attachment end of cablepreparation tool of FIG. 18b according to the present invention;

FIG. 19 is a side view showing insertion of a cable into the firstembodiment of a cable preparation tool according to the presentinvention;

FIG. 20 is a side view showing an inserted cable in the first embodimentof a cable preparation tool according to the present invention;

FIG. 21 is a side view showing a valley locator unit of a fourthembodiment of the cable preparation tool according to the presentinvention;

FIG. 22 is another side view showing a valley locator unit of a fourthembodiment of the cable preparation tool according to the presentinvention;

FIG. 23 is a side view of a fifth embodiment of the cable preparationtool according to the present invention;

FIG. 24 is a cut through view of the cable preparation tool of FIG. 23according to the present invention;

FIG. 25 is a perspective cutaway view of the cable preparation tool ofFIG. according to the present invention;

FIG. 26 is a side view of the valley locator unit of the cablepreparation tool of FIG. 23 according to the present invention;

FIG. 27 is an end view of a spring of the cable preparation tool of FIG.23 according to the present invention; and

FIG. 28 is an end view of another spring of the cable preparation toolof FIG. 23 according to the present invention;

DESCRIPTION OF THE INVENTION

The present invention is a cable preparation tool which allows thepreparation of a coaxial cable having a corrugated outer conductor toreceive a connector in one step. The embodiments of the tool are shownin FIGS. 4-28. The tool 22 allows for the control of trim dimensions foreach component of the cable without measuring. No matter whether the endof the cable before preparation is at the crest 18 or valley 20 of theouter conductor 14, the tool 22 provides the correct trim dimensions foreach component and stops cutting when these dimensions are reached. Thefeatures of the tool 22 which control the preparation of the cable arethe proper positioning of cutting blades along with a crest and valleylocating system.

The tool 22 includes a main body 24, a series of cutting blades and alocating ball system. As shown in FIGS. 4-10, the main body 24 of thetool 22 is shown as a cylinder and preferably made from a light weightmaterial such as aluminum. If a material such as aluminum is used, theinside of the main body 24 should be anodized with a hard coating wherethe tool 22 contacts the cable, so that the two do not gauld. The mainbody 24 has a cable receiving end 26, an attachment end 28 and at leastone jacket removal slot 30 in the outside diameter 32 of the main body24. The cable receiving end 26 is bored out to a diameter of a sizelarge enough to receive a jacketed corrugated cable. The boring out ofthe main body 24 creates a cable receiving area 34 for the cable that isdefined by the inside diameter 36 of the receiving end 26.

The attachment end 28 of the main body 24 is a closed end with a shank38 extending from it and at least one trim end slot 40. All of the toolsshown in FIGS. 4-20 include at least two trim end slots 40. Each trimend slot 40 includes a end cutting blade 42 mounted in the slot 40 fortrimming the end of the cable. Placement and depth of the trim end slots40 and end cutting blades 42 in the attachment end 28 depends on thedesired trim dimensions as will be explained further. The shank 38 iseither a separate piece which screws into the attachment end 28 or isintegral to the attachment end 28. The shank 38 is compatible with ahandle for manual usage or drill chuck for power assisted operation. Theshank 38 features a shoulder 44 that prevents the attachment end 28 fromcoming in contact with a handle or drill chuck. Maintaining thisclearance allows for cable debris to exit from the trim end slots 40without jamming the motion of the tool 22. As shown in FIGS. 11-12, afirst end cutting blade 42B shown in location ‘B’ is responsible forfacing off the dielectric material adjacent to the outer conductor 14.The blade 42B is heat treated to increase blade life and maintainsharpness. This blade 42B also cuts the outer conductor 14 of the cableto length. The blade design and position prevents signal conductivedebris from the outer conductor 14 from embedding in the dielectric 12during the cutting process, as happens when using a hacksaw. A secondend cutting blade 42C shown in location ‘C’ receives the same bladedesign as location ‘B’. This blade 42C is responsible for facing off thefoam dielectric 12 adjacent to the center conductor 14 and on the sameplane as the dielectric 12 faced off by the blade 42B in location ‘B’.These blades 42B, 42C ‘overlap’ the dielectric area they are facing off.The blade 42C in ‘C’ also cuts the center conductor 10 of the cable tolength. The end cutting blades 42 shown in locations ‘B’ and ‘C’ producethe cable end as shown for cable 3 in FIGS. 1 and 2.

The crest and valley locating system include a valley locator unit andsomething to bias the valley locator unit into the cable receiving area34. FIGS. 4-20 show a version of the crest and valley locating systemhaving a ball 50 as the valley locator unit and a spring 52 to bias theball 50 into the cable receiving area 34. The crest and valley locatingsystem shown in FIGS. 4-20 also includes a series of ball holes 48. Eachball hole 48 includes the ball 50, spring 52 and a set screw 54. Theball holes 48 are part of the main body 24 and are located around theoutside diameter 32 of the main body 24. There are two embodiments ofball holes 48. The first embodiment as shown in FIGS. 4-12 has one rowof ball holes 48 circling the diameter of the tool 22. The secondembodiment as shown in FIGS. 13-17 has two rows of ball holes 48, foruse with smaller cables. The smaller cables seem to need a second set ofballs 50 riding in an adjacent valley 20 to the first set of balls 50and valley 20, in order to ensure an accurate trim of the cablecomponents. Factors contributing to the need for a second set of balls50 are that initial cutting of the cable may be at a crest instead ofnormal initial valley cut and the outer conductor 14 tends to be damagedwhen only using one set of balls 50 on the smaller cables. Each ballhole 48 is first drilled of a diameter that will only allow a portion ofa surface of the ball 50 to extend outward into the receiving area 34from the inside diameter 36 of the main body 24. Then, each ball hole 48is drilled almost to the inside diameter 36 of the main body 24 of adiameter to allow the ball 50 to be placed inside of the ball hole 48yet be retained in the hole 48. The drilling of the larger hole ineffect creates a race for the ball 50 to ride in at the bottom of thehole 48 near the inside diameter 36 of the main body 24. The spring 52is placed in the ball hole 48 after insertion of the ball 50. The ballhole 48 is tapped to receive the set screw 54 which secures the ball 50and spring 52 in the ball hole 48.

As shown in FIGS. 4-17 and 19-20, the jacket removal slot 30 runstransverse to the diameter of the cable to be prepared. There is apocket 56 machined in the jacket removal slot 30 for holding a jacketcutting blade 58. The jacket cutting blade 58 is drilled and counterbored to secure it in place with a cap screw 60 using a tapped hole inthe pocket 56. As shown in FIGS. 8 and 10, there can be more than onejacket removal slot 30 positioned along the length of the tool 22. Eachjacket removal slot 30 is for a different trim length of cable's jacket16. Simply mount the jacket cutting blade 56 in the proper jacketremoval slot 30 to obtain the proper jacket trim dimension. A jacketcutting blade 58 is shown in location ‘A’ of FIG. 11 for removing theouter rubberized/plastic jacket 16 of the cable. The blade 58 is heattreated to increase blade life and maintain sharpness. The design ofthis blade 58 features a cutting edge that lifts the jacket 16 away fromthe outer conductor 14 of the cable so as to prevent the blade 58 fromcontacting/damaging the outer conductor 14. Both the angle of the blade58 and the angle of the blade pocket 56 in which blade 58 is situatedare designed so the blade 58 engages and cuts/lifts away the jacket 16when the tool 22 is turned in a clockwise direction. The depth of thepocket 56 is critical in that it has to place the cutting edge of theblade 58 close enough to the outside diameter of the outer conductor 14so as to effectively lift and cut the jacket 16, but at the same time befar enough away so as not to contact or damage the outer conductor 14.The jacket removal slot 30 is designed to provide an exit path for thejacket 16 being removed as well as to provide a view of the removalprocess.

The position of the balls 50 and blades 42, 58 can be controlled whenmanufacturing the tool 22 to accommodate different cable-connectorcombinations. An example is the case for smaller diameter cables. Somesmaller cables require an exposed center conductor 10 that is chamferedor beveled. For this type of preparation a different embodiment of thetool 22 having blades 58 in different positions and two rows of balls 50are shown in FIGS. 13-17. The tool 22 also includes a center conductorreceiving space 62 and a detachable plate 64 in the attachment end 28,so that the rest of the cable components can contact the end cuttingblades 58. The detachable plate 64 houses one of the blades 42, centerconductor receiving space 62 and the shank 38. The trim end slot 40 inlocation ‘B1’ receives a blade 42(B1) responsible for facing off thedielectric 12 material from the inside of the outer conductor 14 to theoutside of the center conductor 10. Location ‘B1’ is a slot in theattachment end 28 of the main body 24. This blade 42(B1) also cuts theouter conductor 14 of the cable to length. The blade design and positionprevents signal conductive debris from the outer conductor 14 fromembedding in the dielectric 12. The trim end slot 40 shown in location‘C1’ receives a blade 42(C1) responsible for beveling the centerconductor 10. The slot 40 in location ‘C1’ and blade 42(C1) are part ofthe detachable plate 64. The blade 42(C1) is heat treated to increaseblade life and maintain sharpness. This blade 42(C1) is positioned toallow the center conductor 10 to feed past the blade 42(C1) as it turnsdown the center conductor 10 and places a bevel at the desired finishlength. The chamfer left on the center conductor 10 is the correctdistance from the dielectric 12 and outer conductor 14. The portion ofthe center conductor 10 that extends beyond this chamfer will have beenturned down to a smaller diameter and extends into the center conductorreceiving space 62. Once the cable is removed from the tool 22, theturned portion of the center conductor 10 will be separately snipped anddiscarded by the installer. The need to snip the center conductor 10 isonly necessary, if the installer did not properly cut the cable tolength (at the center of a valley 20) before applying the tool 22. Asshown in FIG. 18a, the tool 22 can include three end trim slots 40 toallow the trimming of the cable 2 shown in FIGS. 1 and 2, where some ofthe dielectric 12 is exposed between the outer and center conductors 14,10. In this case, there is a first blade 70 positioned deeper in theattachment end 28 for cutting just the outer conductor 14, there is asecond blade 71 for cutting the dielectric 12 which is not as deep asthe blade 70, and finally there is a third blade 72 to cut the centerconductor 10. Keep in mind that all blades 70-72 are the same as blades42 and the separate reference numerals are used only for clarity indescribing the above three bladed scenario. FIGS. 18b-18 d show acombination of the features shown in FIGS. 13-18a to provide adetachable shank end 65 on the attachment end 28 for removing any excesscenter conductor 10, after the center conductor 10 has been chamfered,so that the excess does not have to be hand snipped by the operatorafter removal of the cable from the tool 22. The attachment end 28includes a fourth blade 73 at a proper depth to perform the samefunction as blade 42(C1) of FIG. 17, while having blade 72 of FIG. 18ato cut off the undesired excess portion of the center conductor 10. Thedetachable shank end 65 includes the shaft 38 attached to a shaftsupport structure 75 instead of being directly attached to theattachment end 28. The shaft support 75 includes three support legs 77which extend outwardly away from an open base 83 to a central location79. The shaft 38 then extends outward from the central location 79 ofthe three support legs 77. The openings 81 between the support legs 77provide clearance for derbies from the cable to escape during removal ofvarious portions of the cable. The detachable shank end 65 thereforeprovides room for the fourth blade 72 in a position on the attachmentend 28 which would normally be occupied by the shank 38.

The balls 50 are of a diameter that will occupy the valley 20 of thecorrugated cable to be prepared. Each ball 50 is ‘indented’ into themain body 24 by a spring 52 and set screw 54. The set screw 54 istightened so that the spring 52 biases the ball 50 past the plane of theinside diameter 36 enough so that the ball 50 will best settle in andoccupy the radius of the valley 20 of a corrugated cable withoutdamaging the outer conductor 14. The spring tension is such that as thetool 22 is driven onto the cable, the balls 50 retract when passing overthe crests 18 of the corrugated cable and do not damage the outerconductor 14 at the crests 18. The balls 50 control all dimensionsrequired to prepare the cable for a connector. As described above, eachblade 42, 58 of the tool 22 is positioned a certain distance from thecenterline of the balls 50 depending on the specifications for theconnector. When the balls 50 engage into the valley 18 of thecorrugation, the user feels a release because the blades 42 havefinished their cuts and the balls 50 have relaxed after having passedthe crest 18 where the spring 52 was compressed. When the user feelsthis release he knows that the cable preparation is complete.

As the cable 74 enters the tool 22 in FIGS. 19-20, the first action isthat the jacket cutting blade(s) 58 starts removing therubberized/plastic jacket 16 from the outside diameter of the cable 74,leaving an exposed outer conductor 14. As the tool 22 feeds onto thecable 74, the spring loaded balls 50 make contact with the exposed outerconductor 14, recessing the balls 50 as they pass over the crest 18 ofthe corrugation. As the tool 22 continues to feed onto the cable 74, theend cutting blades 42 remove the outer conductor 14 and dielectric 12leaving a thin ring of dielectric on the center conductor 10, ifspecified for the connector, or facing-off the center conductor 10, ifspecified for the connector. If an exposed center conductor 10 isrequired, the tool 22 would include the center conductor receiving space62 and the additional blades as shown in FIGS. 13-18d, so that the tool22 would keep feeding over the cable 74 until it chamfers and/or facesoff the exposed center conductor 10. When the cable 74 has entered thetool 22 far enough, the spring loaded balls 50 will push themselves intothe first available valley 20 of the corrugation. At this time allcomponents of the cable 74 will have been trimmed to the properspecification for the connector and the tool 22 will stop feedingitself.

When the balls 50 are pushed into the valley 20 of the corrugation bythe action of the spring 52, the jacket cutting blade 58 will haveremoved the correct amount of jacket length from the outside diameter ofthe cable. An end cutting blade 42 will have faced-off the end of thecable ending at the crest 18 of the corrugation on the outer conductor14. Another end cutting blade 42 will have removed the dielectric 12leaving exposed dielectric 12 protruding from the outer conductor 14 orflush with the outer conductor 14, depending on the connectorrequirements. If required, a center conductor beveling blade 42 willhave left a chamfer on the center conductor 10 the correct distance fromthe dielectric 12 and outer conductor 14. Whereby, the center conductor10 that extends beyond this chamfer will have been turned down to asmaller diameter to be discarded separately by the installer or havebeen faced off by an additional blade in the attachment end 28.

FIGS. 21-28 show two alternatives to the crest and valley locatingsystem. FIGS. 21-22 show a first alternative of a spring plunger 100which can replace the ball 50, spring 52 and set screw 54. Essentially,the spring plunger 100 is a set screw 102 with an internal spring 104and plunger 106. The plunger 106 includes a ball shaped end 108 whichacts as the valley locating unit. FIGS. 23-28 show a second alternative.The second alternative includes a spring groove 110, groove openings112, locating plates 114 and a tension spring 116. The spring groove 110encircles the main body 24 and replaces the ball holes 48. There are twogroove openings 112 at the bottom 118 of the spring groove 110. Eachgroove opening 112 is approximately one-fourth to one-half of thecircumference of the inside diameter of the main body 24 at thatlocation. The locating plates 114 are placed into the groove openings112 and rest against remaining portion of the bottom 118 of the springgroove 110. The remaining portion of the bottom 118 of the spring groove110 acts as a support for the locating plates 114. The locating plates114 are secured in the spring groove 110 by the tension spring 116.FIGS. 23-24 and 27 show a wire wrapped spring, while FIG. 28 shows aband spring. The locating plates 114 rest in the groove openings 112 ofthe spring groove 110 until a cable is inserted into the main body 24.The crest 18 of the stripped corrugated cable pushes the locating plates114 outward against the tension of the tension spring 116 as the firstcrest 18 passes between the locating plates 114. As the cable movesfurther into the main body 24, the locating plates 114 are pushed intothe valley 20 of the corrugated cable by the tension spring 116, therebylocating the valley as described for the crest and valley locatingsystem which uses the balls 50.

While embodiments of the invention have been described in detail herein,it will be appreciated by those skilled in the art that variousmodifications and alternatives to the embodiments could be developed inlight of the overall teachings of the disclosure. Accordingly, theparticular arrangements are illustrative only and are not limiting as tothe scope of the invention which is to be given the full breadth of anyand all equivalents thereof.

I claim:
 1. A cable preparation tool, for stripping a coaxial cablehaving a corrugated conductor including crests and valleys, comprising:a main body having a cable receiving end and a cable receiving area forstripping of said cable such that said crests and valleys are exposed;and a crest and valley locating system as part of the main body forlocating the exposed crests and valleys of said corrugated conductor,said crest and valley locating system including at least one valleylocator unit extending into said cable receiving area; and said mainbody including a spring groove encircling said main body, said springgroove including at least one opening into said cable receiving area toreceive said at least one valley locator unit, said opening large enoughto allow at least part of said at least one valley locator unit toextend into said cable receiving area and further including a springsurrounding and in said spring groove to bias said at least one valleylocator unit into said cable receiving area.
 2. The cable preparationtool of claim 1, wherein said valley locator unit is a plate.
 3. Thecable preparation tool of claim 2, wherein said plate is semi-circular.4. The cable preparation tool of claim 2, wherein said main bodyincludes at least one plate support to prevent said plate from fallinginto said cable receiving area.
 5. The cable preparation tool of claim1, wherein said main body furthers includes at least one blade to removea portion of said cable.
 6. The cable preparation tool of claim 2,wherein said plate is semi-circular; and wherein said main body includesat least one plate support to prevent said plate from falling into saidcable receiving area.
 7. The cable preparation tool of claim 6, whereinsaid main body furthers includes at least one blade to remove a portionof said cable.
 8. The cable preparation tool of claim 1, wherein saidvalley locator unit comprised of at least two plates.
 9. The cablepreparation tool of claim 8, wherein said plates are semi-circular. 10.The cable preparation tool of claim 8, wherein said main body includesplate supports to prevent said at least two plates from falling intosaid cable receiving area.
 11. The cable preparation tool of claim 8,wherein said main body furthers includes at least one blade to remove aportion of said cable.
 12. The cable preparation tool of claim 8,wherein said plates are semi-circular; and wherein said main bodyincludes plate supports to prevent said at least two plates from fallinginto said cable receiving area.
 13. The cable preparation tool of claim12, wherein said main body furthers includes at least one blade toremove a portion of said cable.